In a typical percutaneous translumninal coronary angioplasty (PTCA) procedure, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient and advanced through the aorta until the distal end of the catheter is in the ostium of the desired coronary artery. Using fluoroscopy, a guidewire is then advanced through the guiding catheter and across the site to be treated in the coronary artery. An over-the-wire balloon catheter is then advanced over the guide wire to the treatment site, and the balloon is expanded to reopen the artery. The over-the-wire catheter may have a guide wire lumen which is as long as the catheter, or it may be a rapid exchange catheter in which the guide wire lumen is substantially shorter than the catheter. As another alternative, a fixed wire device may also be used. This device features a guide wire that is affixed to the catheter and cannot be removed.
To help prevent arterial closure, repair dissection, and/or prevent restenosis, a physician can implant an intravascular prosthesis, for example, a stent, inside the artery at the treatment site. The stent may be, for example, a self-expanding stent or a balloon expandable stent. For the latter type, the stent is typically delivered on a balloon and the balloon is used to expand the stent. The self-expanding stents may be made of shape memory materials such as nitinol or of other designs that exhibit self-expansion characteristics.
In certain known stent delivery catheters, a stent (e.g., a coronary vascular stent or another type of stent, such as a peripheral vascular stent, a renal stent, a biliary stent, etc.) and an optional balloon are positioned at the distal end of the catheter. The stent and optional balloon are held down and covered by a delivery sheath. When the distal end of the catheter is in its desired location within the targeted body lumen, the sheath is retracted in a proximal direction on the catheter to expose the stent. After the sheath is removed, the stent is free to self-expand or be expanded with a balloon.